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United States Patent |
5,289,320
|
Kobayashi
|
February 22, 1994
|
Apparatus for defining a position of a lens
Abstract
A lens position definition apparatus is provided in, for example, a camera.
The apparatus includes a base member, a cam mechanism for controlling a
position of the lens relative to the base member along a direction of an
optical axis thereof in accordance with a rotational position thereof
about the optical axis, and at least one spring for urging the lens in a
direction inclined to the direction of the optical axis and the rotation
thereof, in order to enable the cam mechanism to operate.
Inventors:
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Kobayashi; Takumi (Sakado, JP)
|
Assignee:
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Asahi Kogaku Kogyo Kabushiki Kaisha (Tokyo, JP)
|
Appl. No.:
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821072 |
Filed:
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January 16, 1992 |
Foreign Application Priority Data
| Jan 23, 1991[JP] | 3-024992[U] |
Current U.S. Class: |
359/819; 359/823; 396/144 |
Intern'l Class: |
G02B 007/02; G03B 017/00 |
Field of Search: |
359/811-830
372/108
354/286
|
References Cited
U.S. Patent Documents
3049970 | Aug., 1962 | Steinberg | 359/827.
|
4088396 | May., 1978 | Edelstein | 359/822.
|
4442524 | Apr., 1984 | Reeder et al. | 372/108.
|
4487495 | Dec., 1984 | Kimata et al. | 354/403.
|
4720167 | Jan., 1988 | Okura | 359/819.
|
Foreign Patent Documents |
889520 | Dec., 1988 | EP | 359/819.
|
177815 | Apr., 1986 | DE | 359/813.
|
54-71626 | Jun., 1979 | JP.
| |
9328 | ., 1910 | GB | 359/827.
|
Other References
English Language Abstract of Japanese Publication No. 54-71626.
|
Primary Examiner: Arnold; Bruce Y.
Assistant Examiner: Nguyen; Thong
Attorney, Agent or Firm: Sandler Greenblum & Bernstein
Claims
What is claimed is:
1. An apparatus for defining a position of a lens comprising:
a base member;
means for controlling a position of said lens relative to said base member
along an optical axis of said lens in accordance with a rotational
position of said lens about the optical axis, by urging said lens in a
rotational direction, said controlling means further comprising means for
urging said lens in a direction along said optical axis of said lens in
association with said controlling means urging said lens in a rotational
direction; and
at least one spring comprising a coil spring for urging said lens in a
direction inclined to the direction of said optical axis in a rotational
direction opposite said rotational direction of urging by said controlling
means, said at least one spring being tilted such that a central axis
thereof is set to be inclined relative to both the directions of the
optical axis and the rotation of said lens.
2. The apparatus according to claim 1, wherein said control means includes:
a lens actuating member in which the lens is enclosed and which is movable
along the optical axis of the lens and rotatable about the optical axis
thereof; and
a cam mechanism which is provided between the base member and the lens
actuating member so as to regulate the position of the lens actuating
member in the optical axis in accordance with a rotational position of the
lens actuating member.
3. The apparatus according to claim 2, wherein
said base member has a cylindrical supporting portion coaxial with the
optical axis of the lens; and
said lens actuating member has a cylinder portion fitted into said
supporting portion and set to be slidable therein in the direction along
the optical axis and rotatable about the optical axis.
4. The apparatus according to claim 3, wherein
said cam mechanism includes:
at least one axial protrusion formed on the outer peripheral surface of
said cylinder portion; and
at least one cam surface formed on a distal end surface of said supporting
portion and being capable of engaging said axial protrusion.
5. The apparatus according to claim 4, wherein
said axial protrusion is urged to contact said cam surface or the distal
end surface by said spring.
6. The apparatus according to claim 5, wherein said cylinder portion
further comprises connecting means which extends radially from said
cylinder portion, said at least one spring being coupled to said
connecting means and connected to said base member.
7. The apparatus according to claim 1, further comprising a plurality of
said springs.
8. The apparatus according to claim 7, wherein
each of said springs is tilted such that the central axis thereof is set to
be inclined relative to both directions of the optical axis and the
rotation of said lens.
9. The apparatus according to claim 7, wherein
said springs are equiangularly arranged around the lens.
Description
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for defining a position of a
lens, more specifically, to an improvement of an apparatus for defining a
position of a lens along the direction of an optical axis and a rotation
thereof in order to control a position of a lens relative to a camera body
in the direction of the optical axis.
A camera having an auto-focusing device is known in which a lens actuating
member to which a lens is attached is rotatably supported on a cylindrical
member for movement about an optical axis thereof, and the lens actuating
member and cylindrical member are interconnected through a cam mechanism.
The cam mechanism is provided with a cam which is formed on the
cylindrical member and a protrusion which is provided on the lens
actuating member and engaging with the cam. When the lens actuating member
rotates about the optical axis of the lens in accordance with the result
of measuring the distance between the camera and the object to be
photographed, the position thereof in the direction of the optical axis is
changed in accordance with a profile of the cam, thereby adjusting the
focal length of the lens. In order to cause the protrusion of the lens
actuating member to always contact the profile surface of the cam, a first
spring for urging the lens actuating member in the direction of the
optical axis and a second spring for urging it in the rotating direction
are provided between the lens actuating member and camera body.
The first spring, however, is provided in front of the lens actuating
member to urge it toward the cam which is provided behind thereof.
Accordingly, the total length of a lens part incorporated with the
cylindrical member and lens actuating member in the direction of the
optical axis is enlarged. Furthermore, it should be necessary to employ
the first and second springs to accomplish the auto-focusing operation. It
should noted that the camera includes a camera body which has a main body
in which film is loaded and a lens cover which is integrally attached to
the front surface of the main body and in which the lens enclosed in the
cylindrical member is contained.
As a result, in the conventional camera with the first and second springs,
a protruding amount of the lens cover from the front surface of the main
body is relatively large, so that it is difficult to make the conventional
camera compact.
SUMMARY OF THE INVENTION
The present invention was conceived in view of the above-mentioned
circumstances, and it is therefore a primary object of the present
invention to provide an apparatus for defining a position of a lens, which
eliminates a space for arranging a spring for urging the lens in a
direction of the optical axis, thereby rendering the camera to be made in
more compact.
It is therefore another object of the present invention to provide an
apparatus for defining a position of a lens, which shortens the protruding
amount of the lens cover from the front surface of the main body, thereby
allowing the camera to be constructed in more compact form.
In order to accomplish the above-mentioned objects according to a first
aspect of the present invention, there is provided a lens position
definition apparatus which comprises a base member, control means for
controlling a position of the lens relative to the base member in a
direction of an optical axis thereof in accordance with a rotational
position thereof about the optical axis, and at least one spring for
urging the lens in a direction inclined to the direction of the optical
axis and the rotation thereof, in order to enable the control means to
operate.
According to a second aspect of the present invention, the control means
includes a lens actuating member in which the lens is enclosed and which
is movable along the direction of the optical axis of the lens and
rotatable about the optical axis thereof, and a cam mechanism which is
provided between the base plate and the lens actuating member so as to
regulate the position of the lens actuating member along the direction of
the optical axis in accordance with the rotational position of the lens
actuating member.
According to a third aspect of the present invention, the base plate has a
cylindrical supporting portion coaxial with the optical axis of the lens,
and said lens actuating member has a cylinder portion fitted into the
supporting portion and set to be slidable therein along the direction of
the optical axis and rotatable about the optical axis.
According to a fourth aspect of the present invention, the cam mechanism
includes at least one axial protrusion formed on the outer peripheral
surface of the cylinder portion, and at least one cam surface formed on
the distal end surface of the supporting portion and being capable of
engaging the axial protrusion.
According to a fifth aspect of the present invention, the axial protrusion
is urged to contact the cam surface or the distal end surface by the
spring.
According to a sixth aspect of the present invention, the spring is coupled
to the distal end of said cylinder portion at one end, and connected to
said base plate.
According to a seventh aspect of the present invention, the spring is
tilted such that the central axis thereof is set to be inclined relative
to both directions of the optical axis and the rotation of the lens.
According to an eighth aspect of the present invention, there are provided
a plurality of said springs.
According to a ninth aspect of the present invention, each of said springs
is tilted such that the central axis thereof is set to incline relative to
both directions of the optical axis and the rotation of said lens.
According to a tenth aspect of the present invention, the springs are
equiangularly arranged around the lens.
According to an eleventh aspect of the present invention, there is provided
an apparatus for driving a focusing lens adapted to be used in a camera
with an auto-focusing device. The apparatus comprises means for moving the
focusing lens in a direction along an optical axis thereof by causing the
focusing lens to rotate about the optical axis, and means for urging the
focusing lens in a direction inclined to the directions of the optical
axis and the rotation thereof.
The above and other objects, features and advantages of the present
invention will become apparent from the following detailed description
which is to be read in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view showing a lens position definition
apparatus of one embodiment according to the present invention;
FIG. 2 is a side view showing a drawn-in (i.e., contracted) condition of
the lens; and
FIG. 3 is a side view showing a drawn-out (i.e., extended) condition of the
lens.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
Hereinafter, a lens position definition apparatus of one embodiment
according to the present invention will be described in detail with
reference to the drawings.
FIG. 1 shows a shutter control apparatus equipped with a lens position
definition apparatus of one embodiment according to the present invention.
In FIG. 1, the lens position definition apparatus is provided with a base
plate 10 which is fixed to a front surface of a camera body (not shown) by
screws. On the front surface of the base plate 10, a cylindrically shaped
supporting portion 11 which has a central axis substantially aligned with
an optical axis is integrally formed. The front end surface of the
supporting portion 11 is constructed by an arcuate flat surface portion 12
parallel to the front surface of the base plate 10, and a plurality of
recesses 13 equiangularly formed on the flat surface portion 12.
In this embodiment, three recesses 13 are arranged and are 120 degrees
apart. As shown in FIG. 2, each recess 13 is comprised of a slant cam
surface 13a and an upright surface 13b which is perpendicular to the flat
surface portion 12. The depth of the cam surface 13a from the flat surface
portion 12 is set to be gradually increasing in a clockwise direction.
A lens actuating member 20 includes a cylinder portion 21 in which a lens
22 is contained, and by aligning the optical axis thereof with the central
axis of the cylinder portion 21. The cylinder portion 21 is slidably
fitted in the cylindrical supporting portion 11. Accordingly, the lens
actuating member 20 is set to be rotatable about the optical axis of the
lens 22 as well as movable along a direction of the optical axis.
The lens actuating member 20 further includes a plurality of axial
protrusions 23 on the outer circumferential surface of the cylinder
portion 21, each of which extends to be parallel to the optical axis, and
each axial protrusion 23 also has a rounded back side end. In this
embodiment, three axial protrusions 23 are equiangularly arranged
corresponding to the three recesses 13. The rounded ends of the axial
protrusions 23 always contact the front end surface of the supporting
portion 11 by means of springs 31 and 32 (described hereinafter).
Accordingly, the lens actuating member 20 is displaced in the direction
along the optical axis in accordance with the angular position thereof,
when it rotates about the optical axis thereof. That is, the axial
position of the lens actuating member 20 is changed according to the shape
(i.e., the profile) of the front end surface of the supporting portion 11.
It should be noted that a cam mechanism in this embodiment is constituted
by the front end surface of the supporting portion 11 and protrusions 23.
A flange portion 24 is integrally formed on the outer periphery of the
front end portion of the lens actuating member 20. A pair of first and
second arms 25 and 26 which extend in radial directions of the lens
actuating member are provided to the outer periphery of the flange portion
24. The extending directions of these first and second arms 25 and 26 are
opposite to each other, whereby the first and second arms 25 and 26 are
aligned. In other words, these first and second arms 25 and 26 are
attached to the flange portion 24 in positions where these evenly divide
the outer periphery of the lens 22.
The first and second arms 25 and 26 are connected to the camera body
through springs 31 and 32, respectively. The central axes of the springs
31 and 32 are set to be inclined relative to both directions of the
optical axis of the lens 22 and the rotation of the lens actuating member
20. That is, the springs 31 and 32 urge the lens actuating member 20 to
rotate it in a clockwise direction in FIG. 1 or as viewed from the lens
side, as well as to displace (or retract) the lens toward the supporting
portion 11. Accordingly, the axial protrusions 23 always contact the front
end surface of the supporting portion 11.
A third arm 27 which extends radially is integrally formed on the outer
periphery of the flange portion 24 between the first and second arms 25
and 26, especially, in a position where it is displaced in
counterclockwise direction by a predetermined angle from the first arm 25.
The third arm 27 is capable of contacting a protrusion of a lens drawing
mechanism 41 (not shown). The lens actuating member 20 is rotated in a
counterclockwise direction against the urging force of the springs 31 and
32 by means of contact between the third arm 27 and the protrusion of the
lens drawing mechanism 41.
A fourth arm 28 which also extends radially is integrally formed on the
outer periphery of the flange portion 24 between the first and second arms
25 and 26, especially, in a position where it is displaced in a
counterclockwise direction by a predetermined angle from the second arm
26. The fourth arm 28 is capable of contacting a stopper member 19, which
is formed on the base plate 10. The lens actuating member 20 is restricted
to the rotation in the clockwise direction and is urged by the springs 31
and 32, when the fourth arm 28 contacts the stopper member 19.
In FIGS. 2 and 3, the details of the lens actuating member 20, the springs
31 and 32 and the cam mechanism are illustrated. FIGS. 2 and 3 show a
drawn-in condition of the lens 22 and a drawn-out condition thereof,
respectively.
As shown in FIG. 2, one end of each of the springs 31 and 32 are engaged
with hooks 17 and 18, respectively, which are formed on the front surface
of the base plate 10. The other ends of the springs 31 and 32 are coupled
to the first and second arms 25 and 26, respectively, of the lens
actuating member 20. That is, the central axis of each of the springs 31
and 32 and the optical axis are taken to the so-called twisted position or
relation when the lens actuating member 20 is set in the initial position
or it has been rotated in the counterclockwise direction.
As shown in FIGS. 2 and 3, the springs 31 and 32 are inclined with respect
to the optical axis O by 45 degrees, when viewing the lens actuating
member 20 from the side thereof, so that these urge the lens actuating
member 20 to always contact the axial protrusions 23 with the front side
surface of the supporting portion 11. More specifically, the axial
protrusions always contact the flat surface 12 or the cam surfaces 13a of
the supporting portion 11. Furthermore, the springs 31 and 32
simultaneously urge the lens actuating member 20 to rotate in the
clockwise direction, when viewing the lens 22 from the front side.
When the lens drawing mechanism is not operated, and the lens actuating
member 20 is biased by the springs 31 and 32 to be positioned in the most
rotated position in the clockwise direction, the arm 28 of the lens
actuating member 20 is engaged with the stopper member 19, and the axial
protrusions 23 contact the corresponding cam surfaces 13a in the
relatively deep position. Accordingly, the lens actuating member 20 is set
to be in a drawn-in condition or status, as shown in FIG. 2.
When the protrusion of the lens drawing mechanism rotates the lens
actuating member 20 in the counterclockwise direction through the third
arm 27 in accordance with the result of measuring the distance between the
camera and the object to be photographed, the axial protrusions 23 are
displaced along the corresponding cam surfaces 13a toward the flat surface
portion 12, and therefore, the lens actuating member 20 protrudes
forwardly. FIG. 3 shows a drawn-out condition where the lens actuating
member 20 protrudes the most. In the drawn-out condition, the axial
protrusions 23 are engaged with the flat surface 12.
As described above in detail, in this embodiment, the lens actuating member
20 is urged along both of the directions of the optical axis of the lens
22 and the rotation of the lens actuating member 20 by the springs 31 and
32, so that it becomes unnecessary to use two kinds of springs as in the
prior art. In other words, a single form of the springs 31 and 32 for
urging the lens actuating member 20 in a direction inclined to the
directions of the optical axis of the lens 22 and the rotation of the lens
actuating member 20 is only required in this embodiment. That is, the
present embodiment does not include a spring for urging the lens actuating
member 20 only in the direction along the optical axis. According to this
construction, it would be possible to shorten the total length of the lens
part in the axial direction.
As a result, this embodiment can provide the lens position definition
apparatus with the springs 31 and 32, which eliminate a space for
arranging a spring for urging the lens actuating member 20 in a direction
along the optical axis, thereby allowing the camera to be made more
compact. In other words, the springs 31 and 32 of this embodiment can
shorten the protrusion amount of the lens cover from the front surface of
the main body, thereby allowing the camera to be made in more compact.
In this embodiment, furthermore, the springs 31 and 32 are coupled to the
outer periphery of the lens 22 in the equiangular positions. Accordingly,
the urging force applied to the lens actuating member 20 is balanced, so
that the inclination of the lens actuating member 20 relative to the
optical axis of the lens 22 is positively restrained.
It should be clear that the present invention is not limited to the
embodiment described above, nor those illustrated in the drawings, and the
invention can be modified without departing from the spirit and scope of
the claimed invention.
For example, the lens position definition apparatus comprises two springs
31 and 32 in this embodiment. However, the present invention is not
limited to this construction and it is possible to only comprise a sole
spring 31 or 32 for urging the lens actuating member 20 to be inclined to
the optical axis of the lens 22, or it is also possible to include more
than two springs.
Furthermore, the cam surfaces 13a are formed on the front end surface of
the supporting portion 11 and the axial protrusions 23 are provided on the
outer circumferential surface of the cylinder portion 21 in this
embodiment, however, the present invention is not limited to this
construction and it is possible to provide the cam surfaces 13a on the
outer circumferential surface of the cylinder portion 21 and to form the
axial protrusions 23 on the front end surface of the supporting portion
11.
Furthermore, three cam surfaces 13a are provided in this embodiment.
However, the present invention is not limited to this construction and it
is possible that only one cam surface 13a be provided or two cam surfaces
13a are provided.
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